Respirator

ABSTRACT

A portable power-driven respirator controls measured amounts of air (and, if desired, admix gases, such as oxygen) to a patient during inhalation events and from the patient during exhalation events. The events are controlled pneumatically and electrically as to time and rate of occurrence, duration and relationship. Quantities, pressures and times are precisely regulated and monitored automatically with some patient override, provision for deep breaths, some manual control and with indicators and alarms. The alarms include plural inspiratory pressure alarms, some momentary without necessary continuation, and with provision to terminate inhalation under certain conditions and to put the patient effort on an adjustable pressure level with an optional decreasing inspiratory flow pattern available and with auxiliary equipment separately supplied with air so as not to interfere with the operation of the respirator itself.

3 United States Patent [19] Buck et al.

[ Nov. 4, 1975 RESPIRATOR [75] Inventors: Keith E. Buck, Alamo; SotirisKitrilakis; Thomas C. Robinson, both of Berkeley, all of Calif.

[73] Assignee: Teena Corporation, Emeryville,

Calif.

[22] Filed: Oct. 4, 1973 [21] Appl. No.: 403,508

[52] U.S. Cl. l28/145.6; 128/DIG. 17; 128/1458 [51] Int. Cl. A61M 16/00[58] Field of Search 123/1458, 145.6, 145.5,

[56] References Cited UNITED STATES PATENTS 4/1958 Saklad 128/14587/1962 Andreasen..... 128/1458 3,266,488 8/1966 Andreasen 3,351,09211/1967 Ingerfield.... 128/1458 3,523,527 8/1970 Foster 128/14563,714,941 2/1973 Kiplingm. 128/1458 3,729,000 4/1973 Bell 128/14563,730,180 5/1973 Davidson 128/1456 3,794,026 2/1974 Jacobs 128/1458Primary Examiner-Richard A. Gaudet Assistant Examiner-Henry J. ReclaAttorney, Agent, or Firm-Lothrop & West [57] ABSTRACT A portablepower-driven respirator controls measured amounts of air (and, ifdesired, admix gases, such as oxygen) to a patient during inhalationevents and from the patient during exhalation events. The events arecontrolled pneumatically and electrically as to time and rate ofoccurrence, duration and relationship.

Quantities, pressures and times are precisely regulated V and monitoredautomatically with some patient override, provision for deep breaths,some manual control and with indicators and alarms. The alarms includeplural inspiratory pressure alarms, some momentary without necessarycontinuation, and with provision to terminate inhalation under certainconditions 'and to put the patient effort on an adjustable pressurelevel with an optional decreasing inspiratory flow pattern available andwith auxiliary equipment separately supplied with air so as not tointerfere with the operation of the respirator itself.

3 Claims, 5 Drawing Figures US. Patent Nov. 4, 1975 Sheet 10f5 3,916,888

US. Patent Nov. 4, 1975 Sheet 3 of5 3,916,888

HUMIDIFIE 438 FIG 2B w 6 4 3 R 6 9 M W 4 4 m A R T 8 w 4 9 4 3 l 2 w A Ma, 4 T 3 w 3 3 9 6 7 w m RESPIRATOR A respirator closely related to thedisclosure herein is shown in the copending. application of the presentinventors entitled Respirator filed Apr. 26, 1973 with Ser. No. 354,673,now US. Pat. No. 3,840,006 issued Oct. 8, 1974. That application isreferred to for details not repeated herein. For ease in correlation,the reference numerals herein, with a few exceptions, are generally thesame as in that application.

The respirator of the mentioned application has been subjected topractical useage for a considerable period, and it is now desired toretain the valuable features thereof and to improve and to augment thesatisfactory operation thereof.

It is therefore an object of this invention to provide an improvedportable power-driven respirator especially for human use.

Another object of the invention is to provide a respirator in which thealarm system is substantially improved.

Another object of the invention is to provide a respirator in which theinhalation event is especially carefully controlled.

A further object of the invention is to provide an arrangement in whichthe patient effort effect may be readily adjusted.

A still further object of the invention is to provide a respirator witha variable inspiratory flow pattern, particularly one which has adecreasing flow pattern with time.

A still further object of the invention is to provide a respirator whichis capable of operation with auxiliary equipment in such a fashion thatwhether or not the auxiliary equipment is used, the operation of therespirator itself remains unchanged.

A further object of the invention is in general to provide an improvedrespirator.

Other objects, together with the foregoing, are attained in theembodiment of the invention described in the accompanying descriptionand illustrated in the accompanying drawings, in which:

FIG. 1 is a diagram showing the pneumatic circuitry of the respirator;

FIG. 2A is the left-hand portion of a schematic layout showing variousof the pneumatic and electrical circuits of the respirator, while FIG.2B is a similar view complementing the showing in FIG. 2A and showingthe right-hand portion of the layout partially shown in FIG. 2A; and

FIG. 3A is a further diagrammatic showing of circuitry utilized inconnection with the respirator, and FIG. 3B, when placed to the right ofFIG. 3A, cornpletes the diagrammatic showing of the circuitry of FIG.3A.

The respirator pursuant to the invention can be and has been embodied ina number of different forms, and at the present time it is preferredthat the form disclosed herein be utilized. In this instance there isprovided an electric motor 6 connected to a suitable source ofalternating current through a circuit 7 including a main switch 8adapted to be opened and closed by a coil 9 under control from aseparate point. It is preferred that the motor 6 be designed to run on 117 volts alternating current for most uses, and it is also normal tohave a separate motor drive and a separate initial mechanism powered bya l2-volt direct current battery 2 for ambulance use of the respirator.When the battery source is utilized, the switch 8 is opened byappropriate energization of the coil 9.

When in operation, the motor 6 through a shaft 11 drives a compressor 12receiving a supply of atmospheric air through a filter 14 anddischarging through an outlet 17 and a muffler 18 into a supply line 19.From the line 19 a duct 21 leads through an air supply pressureregulator 22 to a suitable vent 23. Air under pressure which may bealternatively supplied from the battery-powered unit is transferredthrough a duct 27 into the line 19. Flow is then into an accumulatorchamber 36 designed to act as a reservoir and expansible andcontractable under air pressure on one side of a movable, boundarydiaphragm and in accordance with spring pressure on the other side ofthe diaphragm. Air from the reservoir 36 can flow into a duct 56 andthrough an air valve 57 having an operator 58 thereon into a line 59opening into a variable chamber 61 also under spring pressure and havinga diaphragm 71, the position of which is effective to control theresponse of a transducer 75, so that the position of the diaphragm 71 isreflected in an electrical change in the circuit of the transducer 75.

Air from the chamber 61 can flow out through a duct 91 to an inhalationor inspiratory flow rate valve 99 (FIG. 2B). To make sure that there isalways a supply of air which can move in the duct 91, even though thevolume controller and its connections may be inoperative, an atmosphericline 92 connects with the duct 91 and is provided with a check valve 93.Normally the valve 93 is closed under the customary super-atmosphericpressure in the line 91 but can open and admit atmospheric air to theline 91 if the pressure in the line 91 is low. The line 91 in enteringthe valve 99 encounters a poppet 94 connected through a stem 96 to adiaphragm 97 forming part of the boundary of a chamber 101. A line 104connected through the duct 56 to the chamber 36 supplies an inhalationpilot operator valve 106 having an operator 107 and at one end joinedthrough a line 108 to the downstream side of the poppet 94, and alsoconnected through a line 109 to the chamber 101.

Also communicating with the chamber on the downstream side of the poppet94 is a chamber 112 entrance to which is controlled by an adjustablepoppet 114. The chamber 112 is in communication with the under side ofthe diaphragm 97 through a duct 122 and also is in communication with aline 123 extending into a yoke 153 (FIG. 1 joined to an airway tube 154extending to the patient inhalation apparatus.

A nebulizer may be supplied with air from the line 123 or may beseparately supplied with air from a compressor 124 having a pressurerelief valve 126 (FIG. 2B) connected thereto. Air supply to thenebulizer from the compressor or from the line 123 is controlled by avalve 127 connected to the line 123 and having an actuator 128 in anelectric line 129 controlled by a switch 131 electrically connected andlater described. The nebulizer may thus be supplied from the compressorwith air entirely separately and distinctly from the air or air-oxygenmixture supplied directly to the patient through the line 123. In thisway operation or non-operation of the nebulizer can be arranged not toaffect the operation of the rest of the respirator. The yoke 153 and theairway 154 have an exhalation branch 156 (FIG. 1) leading through anair-expansible exhalation valve 157 to the atmosphere through a vent Airfor operating the exhalation valve 157 is derived from the accumulatorchamber or reservoir 36 through 56 and through the line an air line 167having a branch 168 extending through a positive end exhalation pressure169 provided with a manual regulator 173. The valve 169 is joinedthrough a line 171 to an exhalation pilot valve 179 having an electricoperator 181. The line 171 has a branch 174 leading through a bleedorifice 176 to a line 177 extending to the atmosphere.

Means are particularly provided for varying the inspiratory flow rateduring a breathing cycle and particularly to make the flow rate decreaseas a cycle of inspiration continues. The air line 167 extends to a tapervalve 144 including an apertured plate 145 having a valve 146 controlledby a flexible diaphragm 147 against which a spring 148 bears. A manualknob 149 controls the pressure of the spring and consequently flowthrough the orifice plate 145 and into a line 151 controlled by a valve162 having an operator 163. When the valve 162 is open, air flowsthrough the line 151 into an actuator chamber 164 of the valve 99 havinga diaphragm 155 therein provided with a stern 159 adapted to move thevalve 94 by pressing on its stem 96. A spring 160 opposes air pressureon the opposite side of the diaphragm 155. This air pressure is normallybled off through an orifice body 161 in FIG. 1 or an equivalent orificebody in FIG. 2B. Thus, when the valve 162 is opened, there is agradually increasing pressure on the diaphragm 155, so that the stern159 tends to close the valve 94 gradually. This affords a decreasingtaper to the inspiratory flow rate during each cycle. The amount ofdecrease or taper depends upon the manual adjustment of the valve 144and is usually set between zero and ninety percent of the full closureof the valve 94.

In addition to the atmospheric air supply, there is provision also forutilizing oxygen in varying proportions to atmospheric air. Oxygen froman external supply 83 (FIG. 2A) is led through a line 84 and through apressure regulator 86 into a line 87 controlled by an oxygen flow valve88 having an electrical operator 89. Outflow from the oxygen valve isthrough a duct 90 joining the duct 59.

In order to control the various instrumentalities described, the volumeor position transducer 75 which translates the axial position of thediaphragm 71 and so the volume of the chamber 61 into a correspondingelectrical signal is operated by the output of an oscillator 188supplied from a suitable voltage source through conductors 186 and 187,the output of the oscillator travelling through a conductor 189 to thetransducer 75. This in turn affords an output through a conductor 191into a demodulator 192 effective through a conductor 193 upon an airvolume detector 194.

The detector 194 is also responsive to a signal from a tidal volumecontrol 196 having a variable output 197 and effective through a switch198 and a conductor 199 joined to the detector 194. Also effectivethrough the switch 198 and a conductor 201 is the variable control 202of a deep-breath increment control 203. The switch 198 is positioned toutilize either one of the controls by means of the operation of adeepbreath volume switch 204 joined by a conductor 205 to a terminal A206, later described.

Parallel to the air volume detector 194 there is provided an oxygenvolume detector 207 receptive to signals through a conductor 208 from anoxygen air ratio control 209 having a variable output 211 and joinedthrough a conductor 213 to a switch 214 also connectable through aconductor 216 to ground. Parallel with the switch 214 is a switch 217connected to a voltage source through a conductor 218 and also joined bya conductor 219 and a switch 221 to an alarm terminal for oxygen B 222,later described. The switches 214 and 217 are preferably joined by agang connector 223 responsive to an activating coil 224 receiving itssignal through a conductor 226 from an oxygen pressure switch 227 joinedto the supply conduit 84. Should the oxygen pressure drop due toexhaustion of the supply, there is an automatic switchover to normal airby coil operation of the switch 214, and the alarm is given by operationof the switch 217. Also for controlling the oxygen, there is in theconductor 213 a manual switch 228 which shunts the variable control 211to afford percent pure oxygen.

The air volume detector 194 is effective through a conductor 231 and anand-gate 232. Also effective on the and-gate 232 through a conductor 233is a signal from a terminal C 234, later described. When the andgate 232is appropriately provided with a pair of signals, the output is througha conductor 236 to an exclusive or-gate 237 effective through aconductor 238 and an amplifier 239 on the operator 58, so that the airvalve 57 is correspondingly opened and closed.

Quite similarly, the oxygen volume detector 207 is effective upon anand-gate 242 through a conductor 243. The and-gate is likewise suppliedwith a signal through a conductor 244 from the terminal C 234. When bothsignals are present at the and-gate 242 there is a corresponding outputsignal through a conductor 247 to the exclusive or-gate 237 and likewiseto an amplifier 248 effective upon the operator 89 of the oxygen valve88. The oxygen valve is thus opened and closed in accordance with thereceived signals.

Also in parallel with the detectors 194 and 207 is a chamber-emptydetector 251 receiving one signal from a variable controller 252 on aresistor 253, as well as from the conductor 193. The detector 251 isconnected by a conductor 255 to a signal terminal 0 256, laterdescribed, and also to an inflation hold timer 257 connected to a signalterminal D 261, later described.

In the operation of the structure, when the chamber 61 is full andprovides a corresponding signal in the conductor 231, that signal isalso transmitted through a conductor 262 to a terminal E 263 (FIGS. 2Aand 3A) and through a conductor 266 (FIG. 3A) to an and-gate 267. Thecompanion enabling signal to the gate 267 is transmitted through aconductor 268 from a terminal F 269 (FIGS. 3A and 3B) and laterdescribed. Upon appropriate signals at the and-gate 267, an inhalationgate 273 is enabled and is ultimately actuated by a respiration ratetimer 274 having a variable control 276 and effective through aconductor 279 upon the trigger of the inhalation gate 273. The conductor279 also has an extension 282 leading to a terminal G 283 appearing alsoin FIG. 3B, to activate an alarm, later described.

When an impulse comes from the inhalation gate 273, it is conductedthrough a lead 286 to an inhalation control 288 having a time limitcontrol 289 and when activated affording a signal through a conductor292 to a terminal H 293 (FIGS. 3A and 2B) and later described. In FIG.2B the terminal H 293 leads through an amplifier 296 to the inhalationpilot operator valve 106 (FIG. 1) through the operator 107 thereof. Moreparticularly, a branch conductor 298 (FIG. 28) extends to the operator163 of the valve 162, which controls the occurrence of the taper on theinspiratory flow rate, as previously described. Also, from the conductor297 there is a branch 299 effective through a switch 131 on the operator128 of the humidifier valve 127, as previously described.

Another output from the inhalation control 288 (FIG. 3A) is through aconductor 302 to an exhalation control 304 having a limit timer 306. Theoutput of the control 304 is effective upon a conductor 308 (FIGS. 3Aand 33) joined to the terminal C 234 (FIGS. 3B and 2A) so that theexhalation signal is afforded the andgates 232 and 242 as previouslymentioned.

The conductor 308 (FIG. 3B) has a branch conductor 316 extending to aterminal .I 317 (FIGS. 3B and 2B) and is consequently efi'ective throughan amplifier 319 and a conductor 321 on the operator 181 for theexhalation pilot valve 179 as previously noted. The conductor 308continues (FIG. 3B) to one of the alarms, in this instance a timedairway disconnect alarm 324 having a timer 326 usually set at aboutonetenth of a second and joined by a conductor 328 to an and-gate 329,the other signal to which is supplied through aterminal K 332 (FIGS. 3Band 28) from an airway disconnect detector 336, as will later bedescribed in connection with various of the alarm structures. When theand-gate 329 is energized, a signal is sent to a control board 339 andhas the effect of illuminating an alarm light 343.

Means are provided for affording a deep breath from time to time. From asuitablesource of voltage available in' a conductor 351 (FIG. 3A) powermay be supplied under control of a manual switch 352 to a conductor 353leading to a control 356 in a synchronizing logic element 357. Adeep-breath timer358 with a variable control 359 is joined through aconductor 361 to the conductor 353, so that either manually or at settimes the synchronizing logic can be energized. Output from the control356 is to a synchronizing and-gate 364 and through a conductor 372 to acontrol board 374, the output of which is effective upon one side of anand-gate 369, the other side of which is connected to a signal divider367 also supplying a signal through a conductor 371 to the and-gate 364.The signal divider 367 receives its impulse through a conductor 366joined to the conductor 292. Thus, when the and-gate 369 is energized,its output is sent through a conductor 377 to a multiple deep-breathgenerator 378 having a switch 379 connecting in circuit any selected oneof a group 380 of resistors.

The output pulse from the deep-breath generator 378 is effective througha conductor 381 on the reset mechanisms of both the control 356 and thecontrol 374. There is consequently, as set and as selected, an outputsignal from the synchronizing logic board 357 in a conductor 386 leadingdirectly to the deep-breath volume terminal A 206 in FIG. 3B and in FIG.2A. This is effective to control the operation of the switch 198 betweenthe tidal volume control 196 and the deep-breath increment control 203.

Joined to the conductor 386 (FIG. 3A) is a conductor 391 extending to aresistor 392 in parallel with a resistor 394 itself connected to theconductor 292. The

resistors are joined by a conductor 395 toan integrator 6 399 is alsoconnected to the conductor 391 extending from the synchronizing logic357 for the deep-breath mechanism by a conductor 400.

The amplifier 397 and the conductor 400 are respectively connectedthrough inverters 404 and 406 into an and-gate 409 also receiving asignal through a conductor 411 from a terminal G 283 FIGS. 3B and 3A) sothat the respiration rate control signal is available at the and-gate409, which furnishes an output through a conductor 412 into an alarmboard 414 effective when the inhalation quantity exceeds the exhalationquantity and acting through a conductor 417 to illuminate a light 418 asan alarm.

; The inflation hold timer 257 (FIG. 2A) affords a signal to theterminal D 261 (FIGS. 2A and 3A) from which the signal is carriedthrough a conductor 421 to an or-gate 422, the output of which travelsthrough a conductor 423 to the inhalation control 288 to terminate itsoutput.

As shown in FIG. 2A, the. chamber-empty detector 251 affords a signal tothe terminal 0 256, likewise shown in FIG. 3B, so that the signal isthen transmitted through a conductor 424 to a control board 425 havingan output carried through a conductor 426 to the other side of theor-gate 422 (FIG. 3A) and having a branch 427 extending to a terminal P428 (FIGS. 28 and 3B) connected through a conductor 429 (FIG. 28) to theactuator 430 of a dump valve 431 efi'ective to connect the conduit 91 toatmosphere and thus immediately drop the pressure in the chamber 61 toatmospheric pressure.

The set function for the board 425 (FIG. 3B) controlling the dump valveoperator and the maximum inspiration pressure is derived ultimately fromthe airway 154 through an airway pressure transducer 432 (FIG. 2B) notonly connected to the airway 154 but likewise connected to the outlet ofthe positive exhalation end pressure valve 169 through a pressureconduit 433. The electrical output of the transducer 432 is carried by aconductor 434 and through an amplifier 435 into a trunk conductor 436.This conductor extends to an amplifier 437 controlled by a variableinput 438 and affording an output through a conductor 439 to a terminalL 440 (FIGS. 2B and 3B) joined to a conductor 441 (FIG. 38) extending tothe set portion of the board 425 and also to an alarm board 442effective to illuminate a light 443 to indicate when a maximuminspiration pressure has been exceeded.

Also joined to the trunk conductor 436 (FIG. 2B) is a patient-effortdetector 444 having a controllable input 446 and leading through aconductor 447 to a terminal M 458 (FIGS. 2B and 3A). A conductor 459having a switch 461 therein leads from the terminal M 458 to an or-gate460 also receiving a signal through the conductor 286 from theinhalation gate 273. In addition, the or-gate 460 receives a signal froma voltage source through a conductor 463 controlled by a manualinhalation switch 464.

The output of the or-gate 460 is into a reset conductor 471 (FIG. 3A)which extends to the reset portion of the respiration rate controller274, to the terminate portion of the exhalation controller 304 and tothe reset portion 473 (FIG. 3B) of a failure-to-cycle control 474 havinga timer 476, usually set at about l5 seconds, so that in the event themechanism does not function properly for that period of time there is asignal supplied through a conductor 47 8 to an alarm board 479 effectiveto illuminatfs as iiidiE'ittSr light 484.

In addition, as shown in FIG. 3B, the signal in the conductor 471 istransmitted through a conductor 486 to an alarm board 487 having a timer488 usually set for approximately three-hundredths of a second and theneffective to afford an output to an and-gate 492 actuating an alarm forthe end of the expiration pressure, but effective only when there is anend expiration pressure signal from a terminal N 494 (FIGS. 3B and 2B),the signal being from the trunk conductor 436 through an amplifier 495having a variable control 496. When the and-gate 492 (FIG. 3B) iseffective, it actuates an alarm board 503 and in turn illuminates analarm light 507.

There is an additional alarm from the terminal B 222 (FIGS. 3B and 2A)to indicate low oxygen pressure. The signal at the terminal 222 iscarried through a conductor 508 into an alarm board 511 and is effectiveto illuminate a signal light 514.

There is also afforded an alarm in the event the main 117-volt powersupply should fail. From a low-voltage source there is power suppliedthrough a conductor 516 (FIG. 3B) to a control switch 517 responsive toa power coil 521 connected in the main power line and normally holdingthe switch 517 open. When the main power fails, the switch 517 closesand serves through a manual disconnect switch 518 to energize aconductor 519 feeding an alarm board 523 to afford illumination of aproper signal light 526.

All of the various signal or alarm boards are connected to a conductor529 extending to an alarm board 532 effective to energize an audiblealarm 527. There is also a manual switch 537 connecting a suitablesource of power through a conductor 542 to reset all of the alarmboards. In addition, the various alarm boards are connected through aconductor 543 to a short interval pulse generator 544 (FIG. 3B)extending through a conductor 546 to a chirp generator 547 and to anintermittent alarm light 548. The chirp generator and the light maylikewise be energized from a terminal Q 549 (FIGS. 3B and 2B) connectedto the airway pressure transducer trunk conductor 436 through aconductor 551 and an amplifier 552 having a variable supply 553. Thus,if the alarms are not promptly reset, the chirp generator is effectiveto give audible alarms at short in-. tervals, say, 10 seconds.

There has thus been provided a respirator having largely automatic butreadily controllable functions to assist in or to maintain respirationand one that is usable under most all practical conditions encounteredeither at fixed locations, such as hospitals, or in transient locations,such as ambulances. The device, per haps with changes in size, is usefulwith adults and also with pediatric cases.

What is claimed is:

1. A respirator comprising a displacement chamber having a wall movabletoward and away from a predetermined location, means for urging saidwall toward said location, means for supplying said chamber with gas ata pressure to urge said wall away from said location, means fordetecting the position of said wall relative to said location, means forcontrolling said supplying means, means responsive to said detectingmeans for actuating said controlling means, a patient airway,

means for connecting said chamber to said patient air- 1 means operatesonly during the inspiration portion of said cycle.

1. A respirator comprising a displacement chamber having a wall movabletoward and away from a predetermined location, means for urging saidwall toward said location, means for supplying said chamber with gas ata pressure to urge said wall away from said location, means fordetecting the position of said wall relative to said location, means forcontrolling said supplying means, means responsive to said detectingmeans for actuating said controlling means, a patient airway, means forconnecting said chamber to said patient airway, a valve in saidconnecting means, means for operating said valve in accordance withpressure in said patient airway, and means additional to said operatingmeans for urging said valve toward closed position.
 2. A respirator asin claim 1 in which said additional means operates in time with thebreathing pressure cycle in said airway.
 3. A respirator as in claim 2in which said additional means operates only during the inspirationportion of said cycle.